1. Field of the Invention
The present invention relates to an instrument panel used in a car and a method for producing such an instrument panel, particularly relates to an instrument panel for covering a folded air bag in an air bag apparatus and a method for producing such an instrument panel.
The present application is based on Japanese Patent Application No. Hei. 10-189510, which is incorporated herein by reference.
2. Description of the Related Art
There is a type of an instrument panel disclosed in U.S. Pat. No. 5,839,752 which is disposed so as to cover a folded air bag.
The instrument panel described U.S. Pat. No. 5,839,752 is formed so that a facing layer constituted by three layers consisting of a skin layer, a foam layer and a barrier layer is disposed on the front surface side of a base. Further, a rupture presumptive portion is disposed in a region for covering a folded air bag so that the rupture presumptive portion is opened so as to enable the air bag to protrude when the air bag is unfolded and inflated.
The rupture presumptive portion was formed so that cutdown portions extending from the base to the foam layer are formed intermittently or continuously along the rupture presumptive portion.
Further, pinholes are formed intermittently in the facing layer along the rupture presumptive portion so that the facing layer is ruptured smoothly at the time of the rupture of the rupture presumptive portion.
The above instrument panel is produced as follows. First, a facing layer constituted by three layers consisting of a skin layer, a foam layer and a barrier layer is vacuum-molded to have a predetermined shape. Next, pins are inserted through the facing layer so that pinholes are intermittently formed along a rupture presumptive portion. Next, the facing layer is set, as an insert, in a mold for molding a base and the mold is clamped. A molding material is injected into the cavity of the mold so that the base provided with the facing layer is insert-molded.
Then, the aforementioned cutdown portions extending from the back surface side of the base to the foam layer are provided to form the rupture presumptive portion by use of an ultrasonic welder, or the like. Thus, the instrument panel could be produced.
In the above instrument panel, however, the pinholes provided in the facing layer are formed after the vacuum-molding of the facing layer.
That is, a perforating step is carried out after the facing layer is molded into a predetermined shape. Accordingly, it is difficult to carry out the perforating step, because the facing layer is hardly bent. Accordingly, the production of the instrument panel takes much labor.
The present invention is designed to solve the aforementioned problem and it is an object of the present invention to provide an instrument panel which can be produced easily and a method for producing such an instrument panel.
In order to achieve the above object, according to an aspect of the present invention, there is provided an instrument panel comprising: a base; a facing layer disposed on a front surface side of the base and including a skin layer, a foam layer and a barrier layer; a rupture presumptive portion disposed in a region for covering a folded air bag, the rupture presumptive portion including cutdown portions formed so as to extend from a back surface side of the base to the barrier layer; and a large number of holes being formed at least in the skin layer so as to cover only the rupture presumptive portion and its vicinity.
According to another aspect of the present invention, there is provided a method for producing an instrument panel comprising the steps of: preparing a pre-facing layer including a skin layer, a foam layer and a barrier layer; forming a large number of holes at least in the skin layer So as to correspond to a portion in which a rupture presumptive portion is to be formed and its vicinity; vacuum-molding the pre-facing layer into a predetermined shape thereby obtaining a facing layer after the step of forming a large number of the holes; insert-molding a base with the facing layer as an insert to dispose the facing layer on a front surface side of the base; and forming a cutdown portion at a portion corresponding to a large number of the hole so as to extend from a back surface side of the base to the barrier layer thereby forming the rupture presumptive portion.
The pre-facing layer can be formed by the following steps of: extrusion molding the skin layer; thermally fusion-bonding the foam layer to the skin layer; and thermally fusion-bonding the barrier layer to a back surface side of the foam layer.
It is preferable that the step of forming a large number of the holes in the skin layer is executed by a perforating step after the thermally fusion-bonding of the foam layer to the skin layer but before the thermally fusion-bonding of the barrier layer.
It is preferable that the step of forming a large number of the holes in the skin layer is executed by a perforating step after the extrusion molding of the skin layer but before the thermally fusion-bonding of the foam layer.
It is possible that the step of forming a large number of the holes in the skin layer is executed by a perforating step after the thermally fusion-bonding of the barrier layer but before the vacuum molding step.
In the instrument panel according to the present invention, at least the skin layer is provided with a large number of holes so as to cover only the rupture presumptive portion and its vicinity. It is not necessary to provide the holes strictly only in the rupture presumptive portion, but the holes may be provided in an area to such an extent that the area includes the rupture presumptive portion. Accordingly, strict controlling of positional accuracy is not required in the perforating step, so that the instrument panel can be produced easily.
Particularly, since strict controlling of positional accuracy is not required in the perforating step, even if the perforating step is performed before the facing layer is vacuum-molded to have a predetermined shape as will be described later and even if the perforated region is displaced at the time of the vacuum-molding of the facing layer thereafter, the perforated region can cover the rupture presumptive portion of the instrument panel securely because the perforated region is provided in a wide area so that the rupture presumptive portion can be ruptured exactly when the air bag is unfolded and inflated.
Further, in the method for producing an instrument panel according to the present invention, the large number of holes provided in the skin layer are formed before the facing layer is formed by vacuum molding. Accordingly, the facing layer at the time of perforation has a shape like a flat sheet before the facing layer is molded into a predetermined shape. The facing layer is therefore easy to handle, so that the facing layer can be perforated easily. Furthermore, because the facing layer is vacuum-molded after the facing layer is perforated, the respective inner circumferential sides of the holes in the skin layer are softened and swollen by heat generated at the time of vacuum molding to thereby block the openings of the holes. Accordingly, the openings of the holes can be made inconspicuous, so that the look of the produced instrument panel can be made nice.
Further, in the case where, the foam layer is thermally fusion-bonded to the skin layer after the skin layer is formed by extrusion molding, and the barrier layer is further fusion-bonded to the back surface side of the foam layer to thereby form the facing layer, the large number of holes to be provided in the facing layer may be formed in a perforating step after the thermal fusion-bonding of the foam layer to the skin layer but before the thermal fusion-bonding of the barrier layer. If so, the circumferential edges of the holes are heated twice at the time of the thermal fusion-bonding of the barrier layer and at the time of vacuum-molding. Accordingly, the openings of the holes can be made more inconspicuous, so that the look of the produced instrument panel can be made nicer.
Further, in the case where, the foam layer is thermally fusion-bonded to the skin layer after the skin layer is formed by extrusion molding, and the barrier layer is further thermally fusion-bonded to the back surface side of the foam layer, the large number of holes to be provided in the facing layer may be formed in a perforating step after the extrusion molding of the skin layer but before the thermal fusion-bonding of the foam layer. If so, the circumferential edges of the holes are heated three times at the time of the thermal fusion-bonding of the foam layer, at the time of the thermal fusion-bonding of the barrier layer and at the time of vacuum molding. Accordingly, the openings of the holes can be made further more inconspicuous, so that the look of the produced instrument panel can be made further nicer.
Features and advantages of the invention will be evident from the following detailed description of the preferred embodiments described in conjunction with attached drawings.